The General Clinical Research Center of the Harvard Medical School is a clincal research unit at the Boston City Hospital consisting of a patient care area in the Thorndike Memorial laboratroy accommodating 18 patients. In the floor beneath the patient area is a core laboratory with facilities for biochemical measurements, for computerized statistical analyses, and for biomedical engineering that is required for the research done in the Clinical Research Center. Without cost to the patient, this Center permits detailed observation of patients under controlled conditions that cannot be conducted in ordinary facilities. At the same time it provides facilities for training highly selected physicians from the entire country to become investigators and clinicians with them throughout their careers. The projects for which the Center is most utilized vary according to the nature of medical problems and necessities. Currently the emphasis is on: the abnormalities in lipid metabolism; the immunological basis of the nephrotic syndrome and of drug-induced diseases; the metabolic alterations during fasting and protracted weight loss in obese patients; a number of problems of malnutrition; and the evaluation of improved methods for cadaveric organ transplantation -- particularly those prevalent in the Inner City population that this hospital serves.